How do i solve this

a. Arithmetic unit (AU). Let A = agazajao and B = b3b2b1bo be 4-bit 2's complement numbers. Shown below is the structure of our arithmetic unit, consisting of four 1-bit Full Adders (FAs), four copies of a circuit N, and interconnections as shown. a3 b3 a2 b2 al b1 ao bo N N KO N ko - ko N k1 KO a3* b3* a2* b2* b1 a0 C4 -1 CO FA FA FA FA $3 $2 $1 SO As specified in the table below, our AU will compute an arithmetic function, depending on the values of control signals k1 and ko: K1 Ko Function 0 0 A PLUS B O A MINUS B 0 A PLUS 1 B MINUS 1 Provide the missing circuitry so that the AU performs as specified. 1. Express aj* and bit in minimal SOP form. Use K-maps to show your work. 2. Draw the circuitry for N, using only NAND gates. Assume that complemented inputs are available. 3. Give a Boolean expression for co as a function of k1, ko